Not really just business, say, you are buying bitcoins yourself. In fact, in which case, the smaller the hashrate remains on the old chain, the more dangerous it became for those left behind.
Well it is not really dangerous. Your money will not be lost.
The worst thing that could happen is you get but scammed but - as I said - it is not so easy a scam to pull.
I edited my original post, sorry.
Now let's say, the scammer sent a payment to someone, which gets confirmed on the new chain, but the old nodes cannot see the larger blocks, so to them the coins do not move at all, either because the new transaction is included in the 'extra space' part of a 2mb block so it is not included in the old chain due to size limit, or because, well, the only miner left in the world that still mines the old chain is the attacker himself. Now the attacker could take as much time as there is in the world, in theory, to wait for, or mine a new block on the old chain, that includes his transaction which spends these same bitcoins already spent on the main chain, then the buyer/merchant will give him fiats/goods for bitcoins that do not exist on the chain 'at large', because he sees the transaction paying him being confirmed on a block relayed by the old node he connects to, and he still wouldn't get these coins after upgrading. Makes sense?